kimi_k2_reasoning_parser.py

# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project

from collections.abc import Sequence
from typing import TYPE_CHECKING, Any

from transformers import PreTrainedTokenizerBase

from vllm.entrypoints.openai.engine.protocol import DeltaMessage
from vllm.logger import init_logger
from vllm.reasoning import ReasoningParser
from vllm.reasoning.deepseek_r1_reasoning_parser import DeepSeekR1ReasoningParser

from .identity_reasoning_parser import IdentityReasoningParser

if TYPE_CHECKING:
    from vllm.entrypoints.openai.chat_completion.protocol import (
        ChatCompletionRequest,
    )
else:
    ChatCompletionRequest = Any


logger = init_logger(__name__)


class KimiK2ReasoningParser(ReasoningParser):
    """
    Kimi K2 parser that delegates to either DeepSeekR1ReasoningParser or
    IdentityReasoningParser based on `thinking` and `separate_reasoning`.

    Unlike DeepSeekV3ReasoningParser which defaults to NOT thinking,
    KimiK2ReasoningParser defaults to thinking mode (uses DeepSeekR1ReasoningParser).
    """

    def __init__(self, tokenizer: PreTrainedTokenizerBase, *args, **kwargs):
        super().__init__(tokenizer, *args, **kwargs)

        chat_kwargs = kwargs.pop("chat_template_kwargs", {}) or {}
        # Key difference: default to True instead of False
        thinking = bool(chat_kwargs.pop("thinking", True))

        if thinking:
            self._parser = DeepSeekR1ReasoningParser(tokenizer, *args, **kwargs)
        else:
            self._parser = IdentityReasoningParser(tokenizer, *args, **kwargs)

    def is_reasoning_end(self, input_ids: Sequence[int]) -> bool:
        return self._parser.is_reasoning_end(input_ids)

    def is_reasoning_end_streaming(
        self, input_ids: list[int], delta_ids: list[int]
    ) -> bool:
        return self._parser.is_reasoning_end_streaming(input_ids, delta_ids)

    def extract_content_ids(self, input_ids: list[int]) -> list[int]:
        return self._parser.extract_content_ids(input_ids)

    def extract_reasoning(
        self, model_output: str, request: "ChatCompletionRequest"
    ) -> tuple[str | None, str | None]:
        return self._parser.extract_reasoning(model_output, request)

    def extract_reasoning_streaming(
        self,
        previous_text: str,
        current_text: str,
        delta_text: str,
        previous_token_ids: Sequence[int],
        current_token_ids: Sequence[int],
        delta_token_ids: Sequence[int],
    ) -> DeltaMessage | None:
        return self._parser.extract_reasoning_streaming(
            previous_text,
            current_text,
            delta_text,
            previous_token_ids,
            current_token_ids,
            delta_token_ids,
        )